Roberto Firmino ruled out for at least a month with 'serious' hamstring injury

Liverpool manager Jurgen Klopp has revealed Roberto Firmino is facing a lengthy spell on the sidelines after sustaining a 'serious' hamstring injury.

The Brazilian forward was hurt in the Reds' 2-0 Champions League victory over Atletico Madrid in midweek after coming on as a half-time substitute at Anfield.

Speaking to Liverpool's official website on Friday, Klopp said: "Bobby is not good news with a serious hamstring injury, really unfortunate.

"We don’t know exactly how long he will be out but it will be not now after the international break directly. We have to work on that.”

When asked for a timeframe in his pre-match press conference ahead of facing West Ham on Sunday, he added: "Weeks still, I don't know exactly. More than four, which I would consider a serious injury.

"Then we have to see, it's Bobby, he's a quick healer."

The 30-year-old will miss Liverpool's tricky looking trip to the high-flying Hammers in the Premier League on Sunday ahead of the international break, as well as Brazil's key World Cup qualifiers against Colombia and Argentina later this month.

The prognosis suggests the forward will also be absent for the visit of Arsenal on 20 November following the international pause, as well as matches against Porto and Southampton this month, returning after the Merseyside derby on 1 December at the very earliest.

The German also revealed that Joe Gomez (calf) and Curtis Jones (eye) will miss the match at the London Stadium. Gomez was not included in Gareth Southgate's senior England squad, and Jones has been omitted from the Under-21s.

“Curtis is a completely different story [to Firmino]," Klopp continued. "He was very unlucky in training – he got a finger that scratched the eye. I had a lot of injuries to players in my career, that was not involved. He is on the way back but we have to see how long exactly. 

“He will be back after the international break, for sure, but in the international break we have to see when he can start doing proper stuff again.

“And Joey, hopefully after the international break as well.”

In more positive news, both Fabinho and Thiago Alcantara are in contention to face the Hammers having made their respective injury returns against Atleti on Wednesday night.

“Very important, you see that. Fab was clear – he was not that long out – that he can maybe go, how we decided then 60 minutes,” Klopp added.

“And swapping that with Thiago was probably exactly the right thing to do, now they should be both a big step ahead, so all good.”